In the 1980s Johnson served three two-year terms in the
Iowa House of Representatives, One of these bills created the Resource Enhancement and Protection program (REAP), which is still operational over 30 years later and has financed thousands of environmental protection initiatives in Iowa; another, the Groundwater Protection Act,
inter alia created and provided financing for the
Leopold Center for Sustainable Agriculture at Iowa State University. In 1993 President Clinton appointed Johnson Chief of the
Soil Conservation Service (SCS), the largest (by "covered" acreage) of the
US Department of Agriculture's 29 agencies, where he served under Secretaries
Mike Espy and
Dan Glickman. During his tenure Johnson worked to expand the mission of the agency to address a more comprehensive set of natural resource problems and opportunities. Reflecting Johnson's work, in 1995 the SCS was renamed the Natural Resources Conservation Service (NRCS). While there, he passionately advocated for public policies to elevate conservation efforts on privately owned “working” land, including cropland, pasture, and rangeland. He also championed expansion of the Wetland Reserve Program and more efficient use of the Environmental Quality Incentives Program (EQIP) and Stewardship Incentives Program to reward farmers and ranchers who sought to achieve multiple environmental benefits on their working lands—e.g. soil erosion control, water quality improvement, provision of wildlife habitat, and maximizing biological diversity ("multiple use policy"). In addition, he worked with the Secretary's office to create a National Conservation
Buffer Initiative that made use of the continuous sign-up provision of the Conservation Reserve Program and other USDA conservation cost-share programs to greatly expand the use of filter strips, grassed waterways, and other conservation buffer practices. As Chief, Johnson worked aggressively throughout his tenure to emphasize the importance of using sound science to undergird agency programs and practice and took creative action to strengthen agency's scientific capabilities through creation of institutes and reshaping technical units. He also sought to bring about cultural change within the agency to accommodate greater diversity in the agency's workforce. He retired from the NRCS in 1997. In the early 2000s he served as head of the
Iowa Department of Natural Resources under Governor
Tom Vilsack. Among other priorities, at the DNR he championed state support for
buffer strips. In 2004 he unsuccessfully ran for the
US House of Representatives. He also served on the Board on Agriculture of the
National Academy of Sciences and the Board of Directors of the Iowa Peace Institute, as well as on the boards of a number of environmental and conservation organizations, including the
Aldo Leopold Foundation, Winneshiek Energy District,
The Land Institute, the
Iowa Natural Heritage Foundation, the Iowa
Nature Conservancy, the Institute for Alternative Agriculture, the Pine Bluff 4-H Camp, and Iowa's Environmental Protection Commission. ==Later life==